JPH06298041A - Belt pretensioning device - Google Patents

Abstract

PURPOSE: To provide a belt pretensioner in which the reliable deceleration of a piston in the piston and cylinder linear driving device of a vehicle safety belt system can be guaranteed even under the action of a powerful gas generator by arranging a deformable stopping member on the piston. CONSTITUTION: A piston 20 of a piston and cylinder unit 16 and 20 is arranged at an edge part 161 of the cylinder 16, and the piston can be accelerated toward a second edge part 162 forming the constriction part of the cylinder by a gas pressure generated by the gas generator 12. The piston and cylinder unit 16 and 20 constitutes a vehicle sensitive inertia mass with a housing block 14 and a gas generator 12. A deformable member 46 is arranged on the piston 20, and dragged toward the second edge part 162 by the piston at the time of the acceleration of the piston 20, and plastically deformed at the time of any impact with the wall part of the constriction part.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a drive for a belt pretensioner in a vehicle safety belt system.

[0002]

BACKGROUND OF THE INVENTION In a belt pretensioning device as disclosed in U.S. Pat. No. 5,261,697, the drive or unit is a cylinder connected to a housing block, and is received in said cylinder. A pyrotechnic gas generator housed in the piston and the housing block. A cable is coupled to the piston to transfer the piston movement produced by the actuation of the gas generator to the engagement member of the safety belt system. Activation or activation of the gas generator occurs by a vehicle sensitive trigger mechanism. The end of the cylinder is tapered and used as a trap. The piston accelerated by the gas pressure generated by the gas generator is blocked to prevent it from being expelled from the cylinder, for example when a safety belt system is not used or the cable is broken. .
The cylinder and piston are generally made of aluminum. The piston and cylinder together with the gas generator and housing block form a movable assembly used as a vehicle sensitive inertial mass for the trigger mechanism. Due to the absence of a separate inertial mass, it is possible to minimize space requirements and the amount of material and assembly work.

In order to increase the protective action of safety belt systems, heavy duty pyrotechnic linear drives have been introduced to pretension the belt. A strong linear drive increases the force exerted on the cylinder during braking or deceleration of the piston. In particular, under the action of the gas generator and the unused safety belt, the energy of the piston is now sufficient to spread the conical tapered end of the cylinder, which acts as a piston trap. The piston can be ejected from the cylinder.

It is an object of the present invention that the housing block causes the cylinder, even if reliable deceleration of the piston is in the case of enhanced gas generator power.
It is an object of the invention to provide an improved drive for a belt pretensioning device which is ensured without compromising the vehicle-sensitive function of the assembly, which is constructed as having a piston and a gas generator housed therein. .

It is an object of the invention, according to the invention, to impinge on a wall part made of a plastically deformable material which is driven by the piston towards the tapered end of the cylinder with acceleration of the piston and which defines the tapered end. It is achieved by providing a piston with which is plastically deformed.

[0006]

SUMMARY OF THE INVENTION The invention is based on the concept that the distance between the center of gravity of a piston-cylinder linear drive and the pivot axis is an important parameter for the response sensitivity that causes ignition of the gas generator. . Therefore, in the case of the design of the belt pretensioning device according to the invention, special attention should be paid to the piston
Paid for the resulting center of gravity in the case of a cylinder linear drive. By arranging the deformable damping member on the piston, it is possible to obtain a simple adjustable restraining action at the end of the cylinder, as required. Since the mass of the deformable braking member is adjacent to the initial center of gravity of the piston-cylinder linear drive, the arrangement of the deformable braking member does not blame any adverse effect on the center of gravity. Therefore, all piston-cylinder linear drive designs or configurations of the type initially mentioned can be equipped with deformable members without the response sensitivity of the piston-cylinder linear drive being substantially impaired. Is. It is even possible to adjust the response sensitivity to some extent by modifying the mass and design of the deformable member.

The blocking effect can be optimized by the choice of the geometry of the deformable damping member and the piston. According to an advantageous embodiment, the piston has an axial neck with a reduced cross-sectional area at the end facing the second end of the cylinder, and the deformable member with a sleeve-like profile is a piston. Slipped on the neck. It is further advantageous if the deformation space is arranged in the deformable member such that a preferentially directed deformation of the deformable member occurs when the piston is blocked. For this purpose the outer and / or inner surface has a modified, i.e. non-circular, profile, in particular in the form of axially extending projections and / or grooves.

The blocking effect on the piston can be further optimized by suitable choice of materials. The melting temperature of the material of the deformable member should be higher than the autoignition temperature of the material of the pyrotechnic gas generator. This can be accomplished by employing a metallic solder-like material such as a tin alloy. The restraining action on the piston by the deformable member thus remains valid even if the vehicle ignites and the gas generator is ignited by the action of heat.

Further developments and advantages of the present invention will be understood from the disclosure by the detailed description given below in connection with the drawings.

[0010]

1 is a cross-sectional view of a portion of a belt / cylinder linear drive 10 of a belt pretensioner for a vehicle safety belt system. The piston-cylinder linear drive 10 includes a gas generator 12, a housing block 14 in which the gas generator 12 is placed in a suitable recess, a cylinder 16 having a tapered end portion 18 and within the cylinder 16. It is composed of a piston 20 which can be slid by the above and is connected to a cable 22.

The first end of the cylinder 16 is threaded and is screwed into a corresponding threaded recess in the housing block 14. The piston 20 is arranged at the first end 161 of the cylinder 16 in a neutral position in which it does not move. Adjacent to the piston 20 is a pressure chamber 24, which is connected to the receiving space of the mechanically ignited gas generator 12. It is of course possible to provide other ignition or ignition devices, such as electric ignition devices. However, due to the mechanical ignition of the gas generator 12, it is cocked against a spring or a double leg torsion spring by abutting against the housing block 14.
There is an impact lever. Ignition lever or impact lever 28
Is journaled or pivotally supported by a pin 30 in a support housing 32 in a pivotable manner. Housing block 14 is also pivotally mounted by support pins (not shown). The gas generator 12 is connected at its end projecting from the housing block 14 with an ignition device having an ignition pin 36. The outer end of the ignition pin 36 projects from the bottom surface of the gas generator 12.

The ignition lever 28 is urged by the spring 26 in a direction that coincides with the movement of the ignition lever 28 toward the ignition pin 36. As shown in FIG. 1, the ignition lever 28 is in its neutral position. A neck 38 molded onto the firing pin 28 and projecting toward the housing block 14 and having a stepped surface is in contact with a retaining surface 40 at the adjacent end of the housing block 14. Therefore, the spring 26 not only loads the ignition pin 28, but also loads the housing block 14 so that the housing block 14 is maintained in its stable neutral position.

Cable 22 extends through pressure chamber 24 and through a hole 29 that substantially conforms to the cross section of cable 22. The cable 22 may be equipped with a belt drum (not illustrated) or a belt buckle, also not illustrated, in a known manner.

The piston 20 is crimped onto the cable 22 and has a seal 44 in the circumferential groove (see FIGS. 1 and 2) so that the gas pressure generated by the gas generator 12 is the piston 20. Can work in a lossless manner. At its front end the piston 20 has a sleeve-like neck 201 (see FIG. 2), said neck 201 being connected by a conical portion 202 to the rest 203 of the piston 20. The cylinder 16 and the piston 20 each have a circular cross section over their entire length.

A deformable damping member 46 is slidably mounted on the neck 201, said deformable member 46 extending axially therethrough and adapted to the neck 201 of the piston 20 in a cylindrical recess 48. Have. Sleeve-shaped deformable member 4
6 is shown in detail in FIGS. 3 (a) and 3 (b).
Grooves 50 are machined on the inner surface of the deformable member 46, and ridges 51 as protrusions extending in the axial direction are left between the grooves 50. The outer envelope surface of the deformable member 46 is provided with ridges 52 as protrusions, and these ridges 52 extend in parallel to the central axis of the cylinder 16 like the ridges 51. Free or second end 162 of cylinder 16
Shortly before, the cylinder 16 is frustoconical in its geometry, so that the cross-sectional area of the hole in the cylinder 16 tapers at the distal end 18 toward the second end 162.

The piston / cylinder linear drive device 10 is
Relative identification such that the housing block 14 can be pivoted from the neutral position shown in FIG. 1 toward the actuated or unstopped position when subjected to the inertial forces that occur during vehicle deceleration. It is installed in the vehicle according to the arrangement direction. At the same time that the trailing edge of the housing block 14 passes the neck 38, the ignition lever 28 is released. The ignition lever 28 is then accelerated by the compression spring 26,
Therefore, the ignition lever 28 is hit against the free end of the ignition pin 36. Upon ignition of the gas generator 12, gas is generated and flows through the pressure chamber 24 in the housing block 14 to the lower end of the cylinder 12 and the piston 20.
Is driven in the cylinder 16 together with the deformable member 46, in addition to which the cable 22 is pulled together.

As soon as the piston 20 reaches the distal end 18 of the cylinder 16, the front portion of the deformable member 46 is struck by the piston 20 against the conically tapering inner bore of the cylinder 16, thus The deformable member 46 is plastically deformed against the resistance of the cylinder wall. The material is in the groove 50 and is peak 51 and peak 52, respectively.
The deformation follows a certain direction, since it can flow into the free space between. Therefore, the deformable member 46 is
0 and plastically deformed to take the contour opposite to the end 18 in the cylinder 16.

The deformable member 46 comprises a metallic solder-like material such as a tin alloy. The melting point of the material is higher than the autoignition temperature of the gas generator 12 and thus the restraining action of the deformable member 46 on the piston 20 is in the case of the action of heat leading to the ignition of the gas generator, eg in the case of a fire. Even that is still guaranteed.

Within the hole 54 of the housing block 14 is a plug 56 which has a melting temperature above the operating temperature range of the gas generator 12 but at most the autoignition temperature of the gas generator 12. Made of equal materials.
The plug 56 softens under the action of heat, for example in the event of a fire, and leaves the hole 54 upon ignition of the gas generator 12 so that no dangerously high gas pressure is created in the pressure chamber 24.

Another embodiment of the deformable member 46 is shown in FIG.
(B) of FIG. 5 and (b) of FIG. The deformable member 46 according to FIGS. 4 (a) and 4 (b) is the deformable member 4 shown in FIGS. 1, 3 (a) and 3 (b).
It is almost the same as 6. However, it is different from those because there are no peaks on the inner surface. In addition, there are more ridges on the outer envelope surface of the deformable member 46. The peaks 52 are beveled in their front part. This is cylinder 16
Of the deformable member 46 against the frustoconical end portion 18 of FIG.

In the embodiment according to FIGS. 5 (a) and 5 (b), the deformable member 46 has no ridges on the outer envelope surface and additional ridges are formed on the inner envelope surface of the deformable member 46. Therefore, it is different from the first embodiment shown in FIGS. 1 and 3A and 3B.

The number of grooves 50 or each of the peaks 51 and 52 and also the size of the deformable member 46 can be modified according to the power of the gas generator 12 and according to the desired distance of the center of gravity from the pivot axis. Such a shape modification influences the plastic deformation of the deformable member 46, so that a reliable stopping effect on the piston 20 is ensured in all possible situations, and thus into the frustoconical end 18 of the cylinder 16. It is possible to adjust the blocking effect on the entry of the piston 20.

As is apparent from the embodiment described, the restraining action of the deformable member 46 can be optimally adjusted by the choice of shape and material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a portion of a pyrotechnic piston / cylinder linear drive according to the present invention.

FIG. 2 is a perspective view of a piston such as the one shown in FIG.

3A and 3B are drawings of the deformable member of FIG. 1, in which FIG. 3A is a perspective view and FIG. 3B is a cross-sectional view of FIG.

4A and 4B are views showing another embodiment of the deformable member according to the present invention, in which FIG. 4A is a perspective view and FIG. 4B is a transverse sectional view of FIG.

5A and 5B are views showing another embodiment of the deformable member according to the present invention, in which FIG. 5A is a perspective view and FIG.
FIG.

[Explanation of symbols]

 10 piston / cylinder linear drive device 12 gas generator 14 housing block 16 cylinder 18 terminal part 20 piston 22 cable 24 pressure chamber 28 ignition lever 32 support housing 46 deformable member 50 groove 51 peak (projection) 52 peak (projection) 161 1st 1 end 162 2nd end 201 neck 202 conical part

Claims (10)

[Claims] 1. A pyrotechnic gas generator (12) and a piston / cylinder unit (16, 20) fixed in a housing block (14), the piston (20) of which comprises a cylinder ( 16) first end (161)
A second end (1) having a constriction of the cylinder (16) arranged by means of a gas pressure generated by the gas generator (12) and coupled with a cable (22).
62), the piston / cylinder unit (16, 20) is accelerated toward the housing block (1).
4) and the gas generator (1) arranged therein.
A belt pretensioning device for a safety belt system of a vehicle, which together with 2) constitutes a pivotally mounted vehicle sensitive inertial mass, said belt pretensioning device of the second part of said cylinder (16).
During acceleration of the piston (20) towards the end (162) of the cylinder, plastic deformation during collision of the wall part of the cylinder (16), which is entrained and carried by the piston (20) and which constitutes the constriction. A belt pretensioning device, characterized in that a deformable member (46) is arranged on said piston (20). 2. The belt pretensioning device according to claim 1, wherein the piston (20) is the cylinder (1).
6) has an axial neck (201) with a reduced cross-sectional area on the side facing the second end and the sleeve-like deformable member (46) has a neck () of the piston (20). 201) A belt pretensioning device that is slipped on. 3. The belt pre-tensioning device according to claim 1 or 2, wherein the outer envelope surface of the deformable member (46) is shaped so as to deviate from a circular shape. 4. The belt pre-tensioning device according to claim 2 or 3, wherein the inner surface of the sleeve-shaped deformable member (46) is shaped so as to deviate from a circular shape. 5. The belt pre-tensioning device according to claim 3 or 4, wherein the shifted shape is the cylinder (1).
6) A belt pretensioning device essentially constituted by the axially extending projections (52). 6. The belt pretensioning device according to any one of claims 1 to 5, wherein the outer envelope surface of the deformable member (46) is relative to the inner envelope surface of the cylinder (16). Belt pretensioning device adapted in cross section. 7. The belt pretensioning device according to claim 1, wherein the constriction is a frustoconical end (18) of the cylinder (16).
And the deformable member (4
6) at its end facing the second end (162) of the cylinder (16), the second end of the cylinder (16)
Belt pretensioner that is at least partially beveled towards the end (162) of the. 8. The belt pretensioning device according to claim 1, wherein the melting temperature of the material of the deformable member (46) is the pyrotechnic gas generator ( Belt pretensioning device with a temperature higher than the automatic ignition temperature of 12). 9. Belt pretensioner according to claim 8, wherein the deformable member (46) is made of a metal solder-like material. 10. Belt pretensioner according to claim 9, wherein the deformable member (46) is made of tin alloy.